build/fuchsia/gn-sdk is a copy of the current GN SDK with paths adjusted.
The rest of build/fuchsia comes from Flutter.

TEST=ci
Bug: https://github.com/dart-lang/sdk/issues/38752
Change-Id: I192cca955d05991bde3931d053df9835c5a2195d
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/334142


Reviewed-by: Zijie He <zijiehe@google.com>
Commit-Queue: Ryan Macnak <rmacnak@google.com>
Reviewed-by: Alexander Thomas <athom@google.com>